Back pain is one of the most widespread deceases in modern societies. After all conservative treatment (non-invasive) options such as medication, physical therapy, chiropractic or osteopathic manipulations and braces are exhausted, patients usually undergo surgical interventions such as laminectomy, discsectomy and finally fusion.
A spinal fusion surgery is designed to stop the motion at a painful vertebral segment, which in turn should decrease pain generated from the joint. New treatment options, usually called Non-Fusion Technologies or motion preservation devices, refer to implants which seek to preserve motion while stabilizing vertebra and relieving pain. There are dynamic stabilization devices (interspinous spacers or pedicle screw based), nucleus augmentation/replacement, facet replacement, annulus repair or total disc replacement.
Dynamic stabilization devices must be flexible in order to allow the spine a normal physiological motion. Thereby it is essential that adjacent levels of the treated segment are not adversely affected by the motion preservation device. Since today, spinal implants—if at all—absorb shocks only elastically (hence affecting adjacent levels), there is a need for true shock absorbing by energy dissipation in motion preservation devices.
Dynamic stabilization devices are designed to provide a certain resistance to the motion of the injured or damaged spine. Often a non-linear resistance over the range of motion in flexion/extension and tension/compression as well as rotation is desirable. Prior art solutions for dynamic stabilization devices are based on complex constructions often containing different materials. Moreover, prior art solutions do not offer any significant passive damping with energy dissipation, which is desired to prevent damage to the adjacent portions of the spine. Hence, there is a need for simple devices build from a biocompatible material with high durability that inherently offers a true damping by energy dissipation. There is moreover a need for simple devices that offer different force-deflection characteristics over their range of strain.